Practices for Providing Zonal Isolation in Conjunction with Expandable Casing Jobs-Case Histories
Expandable casing was once considered only for offshore, high-profile, or very special well conditions. However, with the growth of the technology and experience, expandable casing jobs are becoming routine for use in wells both onshore and offshore. Expandable casing is a combination of technologies, including the expansion method, which can provide zonal isolation in less than optimal cementing conditions. Cementing expandable casing includes the challenges of achieving zonal isolation without the use of pipe movement or pipe centralization. Typically, the placement of cement is conducted at a low pumping rate, which does not facilitate mud removal. Therefore, operators rely on planned squeezes to establish shoe integrity before drilling ahead. This approach can greatly increase the cost of installing an expandable openhole liner. Experience with cementing expandable casing has now developed to the point that best practices for obtaining zonal isolation can be written. These best practices include not only conventional methods like hole conditioning, but also novel means such as incorporation of settable spotting fluids (SSFs). Additionally, cementing designs should consider the long zero gel times required to allow casing expansion without degradation of the cement slurry. Specialized tail and lead cement slurries combine chemical and physical solutions to obtain the goal of expansion without the premature set of the cement. This paper details the lessons learned from recent case histories, as well as the best practices for cementing solidexpandable tubulars. It also reports the success rates of these best practices in field tests and recent solid expandable tubular openhole liner installations.